
/* Copyright (c) Mark J. Kilgard, 1994. */

/**
 * (c) Copyright 1993, Silicon Graphics, Inc.
 * ALL RIGHTS RESERVED
 * Permission to use, copy, modify, and distribute this software for
 * any purpose and without fee is hereby granted, provided that the above
 * copyright notice appear in all copies and that both the copyright notice
 * and this permission notice appear in supporting documentation, and that
 * the name of Silicon Graphics, Inc. not be used in advertising
 * or publicity pertaining to distribution of the software without specific,
 * written prior permission.
 *
 * THE MATERIAL EMBODIED ON THIS SOFTWARE IS PROVIDED TO YOU "AS-IS"
 * AND WITHOUT WARRANTY OF ANY KIND, EXPRESS, IMPLIED OR OTHERWISE,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
 * FITNESS FOR A PARTICULAR PURPOSE.  IN NO EVENT SHALL SILICON
 * GRAPHICS, INC.  BE LIABLE TO YOU OR ANYONE ELSE FOR ANY DIRECT,
 * SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY
 * KIND, OR ANY DAMAGES WHATSOEVER, INCLUDING WITHOUT LIMITATION,
 * LOSS OF PROFIT, LOSS OF USE, SAVINGS OR REVENUE, OR THE CLAIMS OF
 * THIRD PARTIES, WHETHER OR NOT SILICON GRAPHICS, INC.  HAS BEEN
 * ADVISED OF THE POSSIBILITY OF SUCH LOSS, HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE
 * POSSESSION, USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * US Government Users Restricted Rights
 * Use, duplication, or disclosure by the Government is subject to
 * restrictions set forth in FAR 52.227.19(c)(2) or subparagraph
 * (c)(1)(ii) of the Rights in Technical Data and Computer Software
 * clause at DFARS 252.227-7013 and/or in similar or successor
 * clauses in the FAR or the DOD or NASA FAR Supplement.
 * Unpublished-- rights reserved under the copyright laws of the
 * United States.  Contractor/manufacturer is Silicon Graphics,
 * Inc., 2011 N.  Shoreline Blvd., Mountain View, CA 94039-7311.
 *
 * OpenGL(TM) is a trademark of Silicon Graphics, Inc.
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <GL/glut.h>

GLboolean doubleBuffer;

/* ARGSUSED1 */
static void
Key(unsigned char key, int x, int y)
{
	switch (key) {
	case 27:
		exit(0);
	}
}

static void
Draw(void)
{
	glClear(GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

	glStencilFunc(GL_ALWAYS, 1, 1);
	glStencilOp(GL_KEEP, GL_KEEP, GL_REPLACE);

	/* red triangle */
	glColor3ub(200, 0, 0);
	glBegin(GL_POLYGON);
	glVertex3i(-4, -4, 0);
	glVertex3i(4, -4, 0);
	glVertex3i(0, 4, 0);
	glEnd();

	glStencilFunc(GL_EQUAL, 1, 1);
	glStencilOp(GL_INCR, GL_KEEP, GL_DECR);

	/* green square */
	glColor3ub(0, 200, 0);
	glBegin(GL_POLYGON);
	glVertex3i(3, 3, 0);
	glVertex3i(-3, 3, 0);
	glVertex3i(-3, -3, 0);
	glVertex3i(3, -3, 0);
	glEnd();

	glStencilFunc(GL_EQUAL, 1, 1);
	glStencilOp(GL_KEEP, GL_KEEP, GL_KEEP);

	/* blue square */
	glColor3ub(0, 0, 200);
	glBegin(GL_POLYGON);
	glVertex3i(3, 3, 0);
	glVertex3i(-3, 3, 0);
	glVertex3i(-3, -3, 0);
	glVertex3i(3, -3, 0);
	glEnd();

	if (doubleBuffer) {
		glutSwapBuffers();
	} else {
		glFlush();
	}
}

static void
Args(int argc, char **argv)
{
	GLint i;

	doubleBuffer = GL_TRUE;
	for (i = 1; i < argc; i++) {
		if (strcmp(argv[i], "-sb") == 0) {
			doubleBuffer = GL_FALSE;
		} else if (strcmp(argv[i], "-db") == 0) {
			doubleBuffer = GL_TRUE;
		}
	}
}

int
main(int argc, char **argv)
{
	GLenum type;

	glutInit(&argc, argv);
	Args(argc, argv);

	type = GLUT_RGB | GLUT_STENCIL;
	type |= (doubleBuffer) ? GLUT_DOUBLE : GLUT_SINGLE;
	glutInitDisplayMode(type);
	glutCreateWindow("Stencil Test");

	glClearColor(0.0, 0.0, 0.0, 0.0);
	glClearStencil(0);
	glStencilMask(1);
	glEnable(GL_STENCIL_TEST);

	glMatrixMode(GL_PROJECTION);
	glLoadIdentity();
	glOrtho(-5.0, 5.0, -5.0, 5.0, -5.0, 5.0);
	glMatrixMode(GL_MODELVIEW);

	glutKeyboardFunc(Key);
	glutDisplayFunc(Draw);
	glutMainLoop();
	return 0;             /* ANSI C requires main to return int. */
}
